Biohacking: Fasting

Fasting *is* Biohacking

Fasting is not a diet. Fasting is biohacking. It is something you can do to effect change and then measure the results of yourself. Fasting should be accompanied by and followed with an intentional, purposeful diet and an intentional, purposeful lifestyle.

"My fasting increases my insulin sensitivity and decreases ambient cholesterol, glucose, and triglycerides. These are all markers that reduce my susceptibility to metabolic syndromes like diabetes. My fasting accelerates the growth of new neurons and elevates my natural human growth hormone production. This makes me a stronger, smarter version of myself."

Geoffrey Woo, Co-founder / CEO of HVMN, in Why I stopped eating for 7 days

"Fasting and starving live on opposite sides of the world. It is the difference between recreational running and running because a lion is chasing you."

The Complete Guide to Fasting by Jason Fung and Jimmy Moore, page 39

Benefits of Fasting

  • Nutritional Ketosis
    This is when your body, depleted of glucose, shifts to burning fat for fuel.

  • Reducing Insulin Resistance
    If you spent your life fueling yourself with carbs/sugars (converting that to glucose for fuel) then you've probably grown resistant to the insulin your body produces to manage that glucose. Insulin resistance makes it harder for you to burn fat. Too much of this paves the road to becoming a Type 2 diabetic.

  • Promoting Autophagy
    Your body's natural mechanism to break down old and broken cell machinery and recycle them for energy.

  • Increased Human Growth Hormone
    Your body produces this naturally. Production increases during fasting to maintain muscle mass and lean tissues.

  • An Effective Tool for Losing Weight
    Depending on how you craft your fasting/diet/lifestyle regimen, you can lose weight. Once you are burning ketones instead of glycose, the weight you do lose is actual body fat. Weight loss isn't mandatory, however. Many fasters are already at their perfect weight and fast for short periods to support their training regimens with increased autophagy and HGH.

Fed and Fasted

"The process of using and storing food energy that occurs when we eat goes in reverse when we fast. Insulin levels drop, signaling the body to start burning stored energy. Glycogen (the glucose that’s stored in the liver) is the most easily accessible energy source, and the liver stores enough to provide energy for twenty-four hours or so. After that, the body starts to break down stored body fat for energy.

So you see, the body really only exists in two states — the fed (high-insulin) state and the fasted (low-insulin) state. Either we are storing food energy or we are burning food energy. If eating and fasting are balanced, then there is no net weight gain.

The Complete Guide to Fasting by Jason Fung and Jimmy Moore, page 43

The Transition from Fed to Fasted

Summarized from The Complete Guide to Fasting by Jason Fung and Jimmy Moore, page 44 with additional information from Ace, of the Ace of Spades blog

  • Feeding
    You eat normally. Blood sugar rises. When there is too much glucose in the blood, the pancreas releases insulin. Insulin is a hormone that makes cells (like muscle cells) permeable to glucose. Excess glucose is then stored as glycogen in the liver or stored as fat.

  • The Postabsorptive phase (6 to 24 hours into fasting)
    Blood sugar and insulin levels fall. For energy, the liver breaks down glycogen, releasing glucose. Glycogen stores last about 24-36 hours. Your body might start producing grehlin, a hormone to encourage you to eat.

  • Gluconeogenesis
    Glycogen stores have run out. The liver now manufactures new glucose from amino acids in a process called Gluconeogenesis

  • Ketosis (3 days or so into fasting)
    Your low insulin stimulates lipolysis, and your body starts breaking down fat (tryglycerides) for energy, making glycerol, fatty acids and then ketones. After 4 days of fasting, your brain is getting 75 percent of its energy from ketones.

  • Protein Conservation (5 days or so into fasting)
    High levels of HGH maintain muscle mass and lean tissues. Almost all the energy for basic metabolism is supplied by the fatty acids and ketones. Adrenaline levels rise to prevent decreases in metabolic rate.

Different Fasting Regimens

There are many ways you can incorporate fasting into your lifestyle. You don't have to stick with just one, and you can alternate as suits your goals best.

  • The Monk Fast
    Pioneered by, this is a 36 hour water fast.

  • 16/8 "Leangains"
    Pioneered by Martin Berkhan, this is a 16 hour fast followed by an 8 hour feed window. Mark feels that the 16 hour fasting schedule is "an ideal compromise between getting the best out of the fasting, without the negatives that may follow with a longer fast. This leaves eight hours as your eating window ... leaving room for proper pre and post workout nutrition.

  • 20/4 "Warrior Diet"
    Pioneered by Ori Hofmekler in 2001, this 20 hour fast is followed by a 4 hour window. Hofmekler's plan is based on "calorie restriction combined with exercise" that promotes autophagy.

  • "Eat Stop Eat"
    Pioneered by Brad Pilon, "Eat Stop Eat" is another regimen of Intermittant Fasting that has you taking a 24 hour fast, ideally, twice a week.

  • 60 "The Himalayan Fast"
    Promoted by, this is a 60 hour fast. It starts off with a minimal amount of food, 500 calories or less that are high-protein, low carb and high fat, and reduces to a zero calorie water fast if possible.

  • Water Fasting
    Maximum benefits for autophagy and HGH production. You can only drink water, black coffee or unsweetened tea. That's it.

  • Bone Broth Fasting
    Bone Broth contains numerous minerals, vitamins, collagen protein and sodium. It is quickly absorbed by the digestive tract, and many people believe that it has minimal impact on fasting.

  • The 5:2 Diet
    The 5:2 diet involves restricting your calorie consumption to 25% of your energy (calorie) needs, two days a week, and eating normally the rest of the time.

Fasting, the greatest known boost to autophagy

"Nutrient deprivation is the key activator of autophagy. Remember that glucagon is kind of the opposite hormone to insulin. It’s like the game we played as kids – 'opposite day'. If insulin goes up, glucagon goes down. If insulin goes down, glucagon goes up. As we eat insulin goes up and glucagon goes down. When we don’t eat (fast) insulin goes down and glucagon goes up. This increase in glucagon stimulates the process of autophagy. In fact, fasting (raises glucagon) provides the greatest known boost to autophagy."

Dr. Jason Fung, M.D., nephrologist, in Fasting and Autophagy – Fasting 25

Not doing autophagy when you are digesting

"Digestion takes a lot of metabolic energy. After you eat, most of your metabolism is diverted to digestion. That's why you're sluggish or even sleepy after a big meal. (Digestion mostly stops if you're active, by the way, as that energy is diverted to moving around. Digestion would re-start once you start relaxing again) 

Another process that takes a lot of metabolic energy is autophagy, which is the destroying of old, worn-down cells (which may have defects in their DNA and other operative machinery), eating them up and stripping them for spare parts like a burnt-out car, and making new cells (with correctly coded DNA) in their place. 

When you digest, your body doesn't bother doing autophagy, as it's of lower priority. So going for long periods without any ingested food lets the body spend its metabolic energy on autophagy for a change."

Ace, of the Ace of Spades blog, in Fast Friday: The Last Word in Fasting for GAINZZZ

Fasting. Loss of lean mass? No, likely an increase.

"Like cortisol, HGH increases glucose and thus is suppressed during feeding. Fasting is a great stimulus

During fasting, there is the spike in the early morning, but there is regular secretion throughout the day as well. Hartman et al also showed a 5 fold increase in HGH in response to a 2 day fast.

This HGH is crucial in the maintenance of lean mass – both muscle and bone. One of the major concerns about fasting is the loss of lean mass. This does not occur. In fact, the opposite happens – there is likely an increase in lean mass."

Dr. Jason Fung, M.D., nephrologist, in Fasting and Growth Hormone Physiology – Part 3

Fasting alone is not enough

"...the roots of metabolic syndrome lie in the Western diet, with its abundance of sugar, high fructose corn syrup, artificial flavors, artificial sweeteners, and overdependence on refined grains. Societies that have kept their traditional patterns of eating are not afflicted with these metabolic disorders. This book focuses on one particular facet of traditional eating patterns that is virtually forgotten in today’s society: intermittent fasting. However, this is only part of the solution. For optimal health, it is not enough to simply add fasting to your life. You must also focus on healthy eating patterns."

The Complete Guide to Fasting by Jason Fung and Jimmy Moore, page 53

A keto-friendly concoction

In its simplest form, it’s a keto friendly concoction of good coffee, MCT oil and grass-fed butter. It doesn’t really give you much of an insulin spike, the MCT oil is quickly converted into keytones and it has healthy fat. You probably want to avoid it during a fast if you can, but it’s a nice keto friendly boost otherwise.

Q: Will it break a fast?

A: It depends on why you're fasting. It won't take you out of nutritional ketosis, but it will interrupt autophagy because you have to digest it.

Recommended precautions for an extended fast

  • Monitor blood pressure, heart rate, glucose frequently
  • If you do not feel well at any point, you must stop fasting. You may feel hungry, but you should not feel sick.
  • Drink water frequently throughout the day when you fast. Seriously. This is the cardinal rule.
  • Daily Multivitamin
  • To avoid refeeding syndrome, do not extend the fasting period beyond 14 days.
  • When you break your fast, eat gentle things for a day to get the machinery going again, like eggs or guacamole
  • Undertake 7 day fasts no more than once a month
  • Undertake 14 day fasts no more than every 6 weeks
  • Megan Ramos (works with Dr Jason Fung) recommends a teaspoon of salt per day, as well as magnesium supplements. She just puts Himilayan salt rocks on her tongue throughout the day, letting it get absorbed into her bloodstream there, instead of her digestive tract.
  • If you have a medical condition, make sure you do this with medical supervision. Your Doctor may want blood tests throughout.

Is Fasting Dangerous?

Hey, we're not Doctors. We're just a regular family collecting information on the Internet.

Every risk I've seen attributed to fasting seems to be related to poor management: Dehydration, stress, poor sleep, depleted electrolytes, going right back to poor habits when the fast is over.

Of course, this doesn’t include some of the crazy things I’ve read out there that contradicts the actual science. "It will slow down your metabolism!", it doesn’t. "After 3 days, your body eats your organ linings!". Not even remotely true.

Seriously. If you are fat, your body is actually covered in food. Food you need to eat. The world record holder for a therapeutic fast was a fellow from Scotland who fasted for 382 days. He weighed in at 456 pounds, fasted to 180 pounds, and 5 years later weighed 196 pounds.

Stay Hydrated

"Every few blood tests, I've been told I had elevated BUN/Creatinine levels (which usually indicates dehydration or kidney stress)."

"So I just know that I've frequently been dehydrated, and this is a chronic recurring problem for me."

Ace, of the Ace of Spades blog, in Thanks for the Concern and Well-Wishes, and I'm Sorry I Got Defensive